Fuel bowl vent



Nov. 13, 1962 F. J. MARSEE 3,063,687

FUEL BOWL VENT Filed Feb. 15. -l960 INVENTOR. FREDERICK J. MARS EE AmRNEYS United States Patent 3,063,687 FUEL BOWL VENT Frederick J. Marsee, Hazel Park, Mich., assignor to Holley Carburetor Company, Van Dyke, Mich, a corporation of Michigan Filed Feb. 15, 1960, Ser. No. 8,665 4 Ciaims. (Cl. 261-42) The present invention relates generally to carburetors for internal combustion engines. More specifically the invention relates to means for automatically venting the carburetor fuel bowl structure to the atmosphere so as to eliminate fuel vapors during the idle and some off-idle engine conditions.

It is an object of the present invention to provide fuel bowl venting means operable during idle and some offidle engine conditions to connect or vent the fuel bowl directly to the atmosphere and during engine operation at speeds above idle operation to block communication between the fuel bowl and atmosphere.

It is a feature of the present invention to provide in the fuel bowl of a carburetor for an internal combustion engine a vent passage connecting the interior of the fuel bowl to atmosphere, valve means in said vent passage and an additional passage connecting one side of said valve means to a point within the carburetor air cleaner at a point therein subject to pressure drop due to air flow through the air cleaner, said valve means operable to maintain said vent passage open during idle engine operation and closed during normal engine operation.

Still another feature of the present invention is to provide in the fuel bowl of a carburetor for an internal combustion engine a vent passage connecting the interior of the fuel bowl to the atmosphere, a valve seat in said vent passage, a diaphragm, means connecting one side of said diaphragm to a point within the carburetor air cleaner at a point therein subject to pressure drop due to air flow through the air cleaner, a valve stem connected on one end to the other side of said diaphragm and having a valve on the other end thereof registrable with said valve seat, said valve movable with said diaphragm so as to maintain said vent passage open during idle engine operation and closed during normal engine operation.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawing illustrating a preferred embodiment of the invention, wherein:

FIG. 1 is a fragmentary elevational view of a carburetor with parts broken away.

FIG. 2 is a view of the valve structure taken on line 22 of FIG. 1.

The carburetor comprises a body 12 having an upwardly extending air intake portion 14 provided with a choke valve 16 for controlling the flow of air therethrough. The carburetor 10 is provided with a plurality of induction passages one of which is indicated at 18 which communicates between the air intake portion 14 and the engine manifold 20. The induction passages 18 are provided with throttle valves 22 for controlling the flow of combustible mixture therethrough.

A fuel bowl 24 having a float 26 therein is suitably secured to the body 12 which forms a closure for the open side of the fuel bowl 24. Fuel Within the bowl 24 is supplied to the induction passages 18 in a manner well known to the art, such for example as through nozzles, one of which is indicated at 28. The idle fuel system supplies fuel in the correct amount to operate the engine at idle speed. Fuel from the fuel bowl 24 passes through the main jet and through passage 25 to the idle ports 27 and 29 drilled through the side of the carburetor throat.

The fuel bowl 24 has vent means associated therewith ice which includes a diaphragm 30 which defines a chamber 32 with the wall 34 of the fuel bowl 24. A conduit 36 is formed in the body 12 and is provided with a tubular element 38 which extends upwardly into the interior of an air cleaner, a portion of which is shown at 40 as removably supported on a flange 42.

The purpose of this invention is to provide means to prevent fuel vapors from entering the carburetor during the idle range of engine operation when the ambient temperature is excessively high. If fuel vapor enters the carburetor 10 under these conditions erratic fluctuations in engine speed result and, under severe conditions, the engine may stall due to an overrich mixture.

The interior 44 of the fuel bowl 24 has included therein a cover and seat assembly 46 which holds the diaphragm 36 in place. Included in the seat assembly 46 is a passage 48 ending in a valve seat 50. In addition to forming the chamber 32, the diaphragm 30 also forms with the valve body 47 a chamber 52 which is vented to the atmosphere through the passage 54 which extends through a side wall of the fuel bowl 24. Chamber 52 is subjected to atmospheric pressure by means of the passage 54 and as a result thereof subjects the interior of the fuel bowl 24 to atmospheric pressure by means of the conduit 48.

A rod or valve stem 56 which forms part of the entire valve assembly is suitably secured to the diaphragm 30 and extends through the conduit or passage 48, and has on the other end thereof a valve or disc 58 which is movable into and out of engagement with the valve seat 50 depending on the position of the movable wall or diaphragm '30. The valve or disc 58 provides a spring seat 6t) which carries the spring 62 which normally biases the valve 58 in the opening direction so as to move the valve 58 away from the seat 50. The valve 58 remains in an open position during the idle and some off-idle engine positions so as to connect the fuel bowl 24 to the atmos phere. The valve 58 is located in the fuel bowl 24 and prevents fuel vapors from entering the carburetor during the idle range of engine operation. The diaphragm 30 is responsive to a substantial pressure drop due to air flow through the air cleaner 4% under normal operation. During the idle range, air flow through the air cleaner 40 is relatively small and, accordingly, there is a correspondingly small pressure drop from atmospheric pressure. As a consequence of this, the valve 58 remains open and, therefore, all vapors within the fuel bowl 22 will vent directly to atmosphere.

As the speed of the engine increases, there is an in creased quantity of air drawn through the air cleaner 40 and a correspondingly greater pressure drop therein. This drop in pressure is conveyed to the chamber 34 through passages 36 and 38. Accordingly, upon transition from idle to normal engine operation, the pressure drop within the air cleaner 40 is suflicient to permit the atmospheric pressure acting on the underside of the diaphragm 30 to raise the diaphragm 30 thereby overcoming the tension of the spring 62 so as to seat the valve 58 against the valve seat 50. As a result thereof continued operation under normal conditions results in the fuel vapors being eventually drawn through the induction pas sages 18 into the engine.

The conventional vent means, such as a Pitot tube 64 communicating between the air cleaner 40 and the in terior fuel bowl 24, may be provided. However, this particular arrangement forms no part of the present invention.

The phrase idle operation of the engine or ones similar thereto, as used in the claims includes curb idle and some off-idle engine conditions. In the case of curb idle, with the throttle valve closed enough fuel flows from the idle ports to keep the engine operating. When the speed of the engine starts to increase, the idle ports become less eifective and the main fuel supply system begins functioning. However, at some off-idle engine conditions, as the throttle valve starts to open, the pressure drop in the air cleaner drops to a value which is insufficient to overcome the spring 62, and close the valve 58.

The drawings and the foregoing specification constitute a description of the improved fuel bowl vent in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

l. A carburetor for an internal combustion engine hav' ing a barrel including a venturi which is adapted to supply a mixture of fuel and air to the engine, a fuel bowl, a nozzle in the venturi of said barrel, a fuel supply passage connecting said bowl and said nozzle, a throttle valve for controlling the quantity of mixture supplied to the engine, an air cleaner disposed at the inlet end of said barrel, means for preventing flow of fuel vapors from said fuel bowl into said venturi through said fuel supply passage during the idle range of engine operation, said means comprising a chamber having a first wall with an opening therein and a second Wall which is movable, air passage means extending from the side of said second wall exteriorly of said chamber to a position within said air cleaner adjacent the inlet end of said barrel to subject said second Wall to an air pressure equal to atmospheric pressure less the pressure drop through said air cleaner, a vent passage between the atmosphere and said chamber, and a valve controlling said opening and connected to said second wall, said valve being responsive solely to the movement of said second wall and movable in a direction away from said opening to provide communication between said vent passage and said fuel bowl through said opening during the idle range of engine operation, said valve being also movable in another direction to block said opening and prevent communication between said vent passage and said fuel bowl during operation of the engine other than at the idle range.

2. A carbuertor for an internal combustion engine having a barrel including a venturi which is adapted to supply a mixture of fuel and air to the engine, a fuel bowl, a nozzle in the venturi of said barrel, a fuel supply passage connecting said bowl and said nozzle, a throttle valve for controlling the quantity of mixture supplied to the engine, an air cleaner disposed at the inlet end of said barrel, means for preventing flow of fuel vapors from said fuel bowl into said venturi through said fuel supply passage during the idle range of engine operation, said means comprising a chamber having a first wall with an opening therein and a second wall which is movable, air passage means extending from the side of said second Wall exteriorly of said chamber to a position within said air cleaner adjacent the inlet end of said barrel to subject said second wall to air pressure equal to atmospheric pressure less the pressure drop through said air cleaner, a vent passage between the atmosphere and said chamber, a valve controlling saidopening and connected to said second wall, said valve being responsive solely to the movement of said second Wall, and spring means normally biasing said valve in one direction to a position providing communication between theinterior of the fuel bowl and said chamber and vent passage, through said opening during the idle range of engine operation, said valve being also movable in a second direction during operation of the engine other than at the idle range to overcome said spring means and block said opening thereby preventing communication between said chamber and vent passage and the interior of said fuel bowl.

3. The carburetor defined in claim 2 wherein said sec end wall takes the form of a flexible diaphragm.

4. The carburetor defined in claim 2 wherein said spring means is located in said fuel bowl exteriorly of said chamber.

References Qited in the file of this patent UNITED STATES PATENTS 2,796,243 McDutfie June 18, 1957 2,839,154 Sterner June 17, 1958 2,894,734 Wentworth July 14, 1959 

